EVOLUTION
Origin of Life –> Evidence of evolution - homology –> Theory of Evolution - microevolution - mechanism of evolution –> reproduction genetics
Theory explains facts – a framework to ask questions to explain phenomenon
– leads to predictions
– explains laws and facts
- evolution explains biodiversity
- It is the process that results in heritable changes in a population spread over many generations
- inferences: - common ancestor - change over time - heritable change (not physical, environmental change)
- change in the properties of populations of organisms that transcend the lifetime of a single individual
- refers to populations and not to individuals
- changes must be passed on to the next generation - heritable
- any change in the frequency of alleles (subset of genes, particular genes for particular trait - within characteristic there are variations) within a gene pool from one generation to the next
- development of change of characteristics of a line of organisms over time
- change over time in the characteristics of population or of a species
- Wallace: geography with biology, malay archipelago, found 700 species of beetles in Singapore
- Darwin: all organisms are modified descendents of previously existing forms of life
- mechanism
- darwin noticed 13 species of finches within the different islands of Galapagos –> a single ancestral group could give rise to several different varieties or species
- Stanford's 10 lectures on evolution
- Darwin's deductions from his observations:
1. populations have the potential to increase exponentially (becoming more and more rapid)
2. Populations are fairly constant in size
3. Natural resources are limited
4. There is variation within a species, and variation is inherited
1, 2, 3: deduction: only some organisms survive. There is a struggle for existence among individuals in a population.
deduction 1, observation 4: deduction 2: individuals with favourable variations are more likely to survive and reproduce –> accumulation of variation over many generations is evolution.
- gene pool is the total number of genes of organisms in a population
- organisms with useful characteristics are more likely to survive and pass them on to the next generation
- populations change in accordance with environmental factors. changes are driven by environmental pressures.
- natural selection: mechanism to explain origin of species - genetic variation: is heritable –> not base on "needs" or "intent". traits are different from siblings. those with more favourable phenotype survive.
- overpopulation of species: organisms produce more offsprings than can survive
- struggle for survival: for food, space, mate etc. within the species, with other species...
- differential survival and reproduction: favours individual with advantageous (not best, just not the last) traits. will determine the composition of the gene pool: frequency of gene (advantageous) will increase in gene pool –> inherited by more offsprings in the next generation; disadvantageous genes may eventually be wiped out from gene pool.
- evolutionary history shaped by natural selection.
- small change – time –> large change
- overpopulation: more species than can survive, only some survive. excess production results in struggle, competition for food, space and mates.
- traits determined by DNA inherited from parents
- natural selection as central force in evolution
- assumptions made:
- the traits seen must be found in the genes and hence be able to be passed on to the next generation
- traits arose from random events like meiosis and mutation and not by intent (traits must already be in the genotype)
- darwin didn't know about genes and DNA at his time
- variation + differential reproduction + heredity = natural selection
- natural selection: 3 categories:
1. stabilising selection
- normal distribution curve: the majority is the average (in centre range)
2. directional selection
- factors make one extreme of the phenotypic range more favoured
3. disruptive or diversifying selection
- ends up with two
- Larmarck: thought giraffes stretched their necks longer to reach higher leaves –> acquired characteristics can be passed down. acquired: genes not in gene pool. he had false thinking - current findings refute these reasons of selection.
- larmarck's hypothesis - evolution mechanism: features needed for survival are developed in each individual –> characteristics developed/acquired by individuals are somehow passed on to their offspring, who can continue that development –> eventually, over many generations, enough differences have arose to give rise to species
- differences between:
environment changes thus creating a 'need' to change VS variations of inheritable features which already normall exist
- development of new features "in order to survive" or "so that one can survive" VS environment "screens out" features contributing to survival and tends to eliminate others
- newly acquired traits somehow get passed down to offspring VS
Adaptation and fitness
- adaptation, any heritable trait that suits an organism to its function in its niche
- may be structural, physiological or behavioural
- physiology - the way in which a living organism or bodily part functions. physiological adaptations permit the organism to perform special functions (for instance, making venom, secreting slime); but also more general functions such as growth and development, temperature regulation, ionic balance and other aspects of homeostasis.
- genetive adaptation has to be functional in the organism's natural habitat
- it is not acclimatisation: an organism's ability to adapt during its lifetime to changing environmental conditions
- fitness is a measure of how well suited an organism is to survive in its habitat and its ability to maximise numbers of offspring to reproductive age
- survival + fecundity (reproductive success) + mating success –> fitness of the organism
- antibiotic resistance as evidence for micro evolution
- tuberculosis: some strains resistant to drugs - multi-drug resistant tb
Origin of Life –> Evidence of evolution - homology –> Theory of Evolution - microevolution - mechanism of evolution –> reproduction genetics
Theory explains facts – a framework to ask questions to explain phenomenon
– leads to predictions
– explains laws and facts
- evolution explains biodiversity
- It is the process that results in heritable changes in a population spread over many generations
- inferences: - common ancestor - change over time - heritable change (not physical, environmental change)
- change in the properties of populations of organisms that transcend the lifetime of a single individual
- refers to populations and not to individuals
- changes must be passed on to the next generation - heritable
- any change in the frequency of alleles (subset of genes, particular genes for particular trait - within characteristic there are variations) within a gene pool from one generation to the next
- development of change of characteristics of a line of organisms over time
- change over time in the characteristics of population or of a species
- Wallace: geography with biology, malay archipelago, found 700 species of beetles in Singapore
- Darwin: all organisms are modified descendents of previously existing forms of life
- mechanism
- darwin noticed 13 species of finches within the different islands of Galapagos –> a single ancestral group could give rise to several different varieties or species
- Stanford's 10 lectures on evolution
- Darwin's deductions from his observations:
1. populations have the potential to increase exponentially (becoming more and more rapid)
2. Populations are fairly constant in size
3. Natural resources are limited
4. There is variation within a species, and variation is inherited
1, 2, 3: deduction: only some organisms survive. There is a struggle for existence among individuals in a population.
deduction 1, observation 4: deduction 2: individuals with favourable variations are more likely to survive and reproduce –> accumulation of variation over many generations is evolution.
- gene pool is the total number of genes of organisms in a population
- organisms with useful characteristics are more likely to survive and pass them on to the next generation
- populations change in accordance with environmental factors. changes are driven by environmental pressures.
- natural selection: mechanism to explain origin of species
- genetic variation: is heritable –> not base on "needs" or "intent". traits are different from siblings. those with more favourable phenotype survive.
- overpopulation of species: organisms produce more offsprings than can survive
- struggle for survival: for food, space, mate etc. within the species, with other species...
- differential survival and reproduction: favours individual with advantageous (not best, just not the last) traits. will determine the composition of the gene pool: frequency of gene (advantageous) will increase in gene pool –> inherited by more offsprings in the next generation; disadvantageous genes may eventually be wiped out from gene pool.
- evolutionary history shaped by natural selection.
- small change – time –> large change
- overpopulation: more species than can survive, only some survive. excess production results in struggle, competition for food, space and mates.
- traits determined by DNA inherited from parents
- natural selection as central force in evolution
- assumptions made:
- the traits seen must be found in the genes and hence be able to be passed on to the next generation
- traits arose from random events like meiosis and mutation and not by intent (traits must already be in the genotype)
- darwin didn't know about genes and DNA at his time
- variation + differential reproduction + heredity = natural selection
- natural selection: 3 categories:
1. stabilising selection
- normal distribution curve: the majority is the average (in centre range)
2. directional selection
- factors make one extreme of the phenotypic range more favoured
3. disruptive or diversifying selection
- ends up with two
- Larmarck: thought giraffes stretched their necks longer to reach higher leaves –> acquired characteristics can be passed down. acquired: genes not in gene pool. he had false thinking - current findings refute these reasons of selection.
- larmarck's hypothesis - evolution mechanism: features needed for survival are developed in each individual –> characteristics developed/acquired by individuals are somehow passed on to their offspring, who can continue that development –> eventually, over many generations, enough differences have arose to give rise to species
- differences between:
environment changes thus creating a 'need' to change VS variations of inheritable features which already normall exist
- development of new features "in order to survive" or "so that one can survive" VS environment "screens out" features contributing to survival and tends to eliminate others
- newly acquired traits somehow get passed down to offspring VS
Adaptation and fitness
- adaptation, any heritable trait that suits an organism to its function in its niche
- may be structural, physiological or behavioural
- physiology - the way in which a living organism or bodily part functions. physiological adaptations permit the organism to perform special functions (for instance, making venom, secreting slime); but also more general functions such as growth and development, temperature regulation, ionic balance and other aspects of homeostasis.
- genetive adaptation has to be functional in the organism's natural habitat
- it is not acclimatisation: an organism's ability to adapt during its lifetime to changing environmental conditions
- fitness is a measure of how well suited an organism is to survive in its habitat and its ability to maximise numbers of offspring to reproductive age
- survival + fecundity (reproductive success) + mating success –> fitness of the organism
- antibiotic resistance as evidence for micro evolution
- tuberculosis: some strains resistant to drugs - multi-drug resistant tb